The present invention relates to certain substituted indazole compounds, which modulate the activity of protein kinases. The compounds of this invention are therefore useful in treating diseases caused by deregulated protein kinase activity. The present invention also provides methods for preparing these compounds, pharmaceutical compositions comprising these compounds, and methods of treating diseases utilizing pharmaceutical compositions comprising these compounds.
The malfunctioning of protein kinases (PKs) is the hallmark of numerous diseases. A large share of the oncogenes and proto-oncogenes involved in human cancers encode for PKs. The enhanced activities of PKs are also implicated in many non-malignant diseases, such as benign prostate hyperplasia, familial adenomatosis, polyposis, neuro-fibromatosis, psoriasis, vascular smooth cell proliferation associated with atherosclerosis, pulmonary fibrosis, arthritis glomerulonephritis and post-surgical stenosis and restenosis.
PKs are also implicated in inflammatory conditions and in the multiplication of viruses and parasites. PKs may also play a major role in the pathogenesis and development of neurodegenerative disorders.
For a general reference to PKs malfunctioning or deregulation see, for instance, Current Opinion in Chemical Biology 1999, 3, 459-465.
A subset of PK is a group of membrane receptors with intrinsic protein-tyrosine kinase activity (RPTK). Upon binding of grow factors, RPTKs become activated and phosphorylate themselves and a series of substrates in the cytoplasm. Through this mechanism, they can transduce intracellular signalings for proliferation, differentiation or other biological changes. Structural abnormalities, over-expression and activation of RTPKs are frequently observed in human tumors, suggesting that constitutive ignition of the signal transduction leading to cell proliferation can result in malignant transformation. Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor belonging to the insulin receptor subfamily of RTKs: the ALK gene is located on chromosome 2 and is expressed mainly in neuronal cells, especially during development. The ALK gene is involved in a balanced chromosomal translocation with the Nucleophosmin (NPM) gene on chromosome 5 in a large subset of Anaplastic Large Cell Lymphomas (ALCL). In the ALK+ ALCL, as a result of the translocation, the NPM ubiquitous promoter drives an ectopic expression of the fusion protein in which the NPM moiety dimerizes and the ALK kinase domain undergoes auto-phosphorylation and becomes constitutively active.
Many data from the literature have demonstrated that the NPM-ALK fusion protein has a strong oncogenic potential and its ectopic expression is responsible for cellular transformation. Moreover, the constitutive expression of human NPM-ALK in mouse T-cell lymphocytes is sufficient for the development of lymphoid neoplasia in transgenic animals with a short period of latency.
ALCL is a defined disease characterized by the surface expression of the CD30 antigen (Ki-1), and accounts for 2% of adult and 13% of pediatric non-Hodgkin's lymphomas, affecting predominantly young male patients. ALK+ ALCL accounts for 70% of all ALCLs and is an aggressive disease with systemic signs, and frequent extranodal involvement (bone marrow, skin, bone, soft tissues).
About 15-20% of ALK-expressing ALCLs were found to bear a different chromosomal translocation, involving the cytoplasmic portion of ALK, with different N-terminal moieties, all resulting in constitutive activation of the ALK kinase domain.
Moreover, cell lines established from solid tumors of ectodermal origin like melanomas, breast carcinomas, as well as neuroblastomas, glioblastomas, Ewings sarcomas, retinoblastomas, were found to express the ALK receptor.
In conclusion, interfering with the ALK signalling likely represents a specific and effective way to block tumor cell proliferation in ALCL and possibly other indications. The insulin-like growth factor 1 receptor (IGF-1R, IGF1R) is also a member of the insulin receptor subfamily of RTKs.
There exist several lines of evidence suggesting that IGF-1R signaling can contribute to tumorigenesis, and that interfering with IGF-1R function represents a valid therapeutic option in cancer. For an overview of IGFs and IGF-1R signalling, physiological function, and detailed description of the evidence supporting involvement of this system in human cancer that is summarised above, as well as in other pathologies, the reader is directed to the many reviews on the subject and references contained therein, for example Baserga R. et al, Biochim Biophys Acta vol. 1332, pages F105-F126, 1997; Khandwala H. M. et al, Endocr Rev vol. 21, pages 215-44, 2000; Le Roith D. et al, Endocr Rev vol. 22, pages 53-74, 2001; Valentinis B. et al, Mol Pathol vol. 54, pages 133-7, 2001; Wang Y. et al, Curr Cancer Drug Targets vol. 2, pages 191-207, 2002; Laron, Z. J Clin Endocrinol Metab vol. 89, pages 1031-1044, 2004; Hofmann F et al, Drug Discov Today vol. 10, pages 1041-7, 2005.